I. Field of the Invention
The present disclosure relates to vibrating conveyors with a flat horizontal conveying pan referred to as a trough, and more particularly, to a vibratory conveyor with an angle of attack defined as an amplitude with a vertical and horizontal component design, particularly of the two mass sub-resonant natural frequency type powered by a single motor with counterweighted wheels capable of conveying in both the forward and reverse flow direction.
II. Description of the Prior Art
Bi-directional vibratory conveyors or feeders have substantial applications in a variety of fields. One typical application is in foundry operations wherein, for example, foundry castings may be delivered to a conveyor energized to feed the castings to one end or the other, depending upon where it is desired to locate the castings.
Another typical application is in the bulk operations of granular materials wherein, for example, sugar, sand, stone, flour, cement, and various other chemical compounds may be delivered to one end or the other in the same way. Additionally, the conveyors may also move combinations of these object, granular and powder materials.
A conventional bi-directional conveyor made according to the prior-art will typically include two motor and two drive arrangements that are connected to drive slats supporting the two motors and drives. The slats are set in line with the angle of attack of the two drives. The drives are angled at an angle of attack of 45° creating an angle of 90° between the two drives resulting in isolating one drive from the other through the drive slats operating at 90° from the drive angle of attack of the non-operating drive. Each motor has a pair of counterweight wheels set at a force that vibrates the pan at an amplitude that moves the material at the desired rate.
This prior-art conveyor poses a number of problems, the greatest of which is the use of two separate drive assemblies whose operation is essentially a brute force system. In other words, the operating drive mass becomes a part of the trough mass and the non-operating drive mass becomes isolated from the operating system. This creates a problem for the non-operating motor. The non-operating motor bearings are subject to a percentage of the dynamic load transmitted through the isolation slats. This dynamic load creates “false brinnelling” which causes flattened surfaces on the bearing races and motor shaft. The result being faster than normal wear.
In other examples of bi-directional conveyors, Musschoot U.S. Pat. No. 3,068,996, issued Dec. 18, 1962, proposes a system that uses air bags as reactor springs set in a two mass system using two separate drives for the purpose of conveying material in opposite directions. When one drive is activated, the second drive air bag reactor springs are deflated so that the pressure sets the air bag spring rate for the second drive at an isolation rate while the inactive drive motor remains running for the purpose of eliminating false brinnelling in said motor. Besides this invention requiring two separate motors, both motors must be continuously run while the conveyor is in operation requiring double the power needed to accomplish the task.
Schrader, U.S. Pat. No. 3,746,149, issued Jul. 17, 1973, and entitled “Reversible Vibratory Feeder”, proposes a system that uses air bags as reactor springs set in a single mass system. However, the counterweight wheels needed to accomplish a reasonable stroke is about five times greater than what is needed in a two mass system. As a result, the motor horsepower required is much greater than the power required in a two mass system.
Thomson, U.S. Pat. No. 5,934,446, issued Aug. 10, 1998 uses a quick return flat (zero degree angle of attack) stroke. A forward momentum of the material is created by imposing an input of momentum for a set time. On the return flat stroke, the time input is less than the time input of the forward flat stroke. The result being a forward momentum greater than the reverse momentum creating a forward material flow. By reversing motor rotation, material flow is reversed. This system requires only one motor and only one drive assembly. However, the rate of material travel is greatly restricted for the equivalent stroke of the other inventions with a greater than zero degree angle of attack.
Similarly, the Musschoot U.S. Pat. No. 6,029,796, issued Feb. 29, 2000, uses a flattened elliptical stroke that generates a forward momentum to the material on the upward stroke of the flattened ellipse by creating a plus g-force and a slightly lesser g-force on the return stroke which subtracts from the momentum of the material travel speed. Although this arrangement creates a bi-directional material travel flow by reversing motor rotation, the travel speed of the material is greatly limited because of the relatively small difference of momentum created by the forward and reverse vertical stroke.
These prior art systems illustrate the advantage a two mass or a single mass sub-resonant natural frequency conveyor wherein the motor counterweighted wheels are considerably smaller than the counterweighted wheels on the brute force prior-art conveyor required to generate the same amplitude. Such a design would result in less torque required to rotate the smaller wheels which equates to a smaller horsepower motor.
There remains no system that is truly a bi-directional, two-mass, single motor design and at an angle of attack greater than zero degrees. Accordingly, there exists a need for such a system to provide a bi-directional conveyor to operate at a reduced power requirement.
It is a general object of this disclosure to provide an improved conveyor which utilizes less and smaller component parts, as compared to current practice, thereby greatly reducing manufacture and maintenance costs.
It is another general object of this disclosure to provide a bi-directional conveyor that will drive material more efficiently because of a set angle of attack greater than zero degrees.
It is more specific object of this disclosure to provide a bi-directional conveyor that is isolated from the ground.
These and other objects, features and advantages of this disclosure will be clearly understood through a consideration of the following detailed description.